backport #249

Author: cowtowncoder

build.sbt

@@ -5,17 +5,19 @@ name := "jackson-module-scala"
 
 organization := "com.fasterxml.jackson.module"
 
-scalaVersion := "2.11.7"
+scalaVersion := "2.11.8"
 
-crossScalaVersions := Seq("2.10.6", "2.11.7")
+crossScalaVersions := Seq("2.10.6", "2.11.8")
 
 scalacOptions ++= Seq("-deprecation", "-unchecked", "-feature")
 
 // Temporarily disable warnings as fatal until migrate Option to new features.
 //scalacOptions in (Compile, compile) += "-Xfatal-warnings"
 
 // Ensure jvm 1.6 for java
-lazy val java6Home = new File(System.getenv("JAVA6_HOME"))
+lazy val java6Home = Option(System.getenv("JAVA6_HOME")).map(new File(_)).getOrElse {
+  sys.error("Please set JAVA6_HOME environment variable")
+}
 
 javacOptions ++= Seq(
   "-source", "1.6",